Internal combustion engine



March 22, 1932 J. C. PETERSON INTERNAL COMBUSTION ENGINE Filed June 25, 1928 3 Sheets-Shet 1 3 Pg] T 1 a a l W 1 Y I 4/ 44 Y 8' A a l g l 4 40 I fl 9 4 5 H -ZZ Z I g g.

Inventor:

March 22, 1932. J. c. PETERSON INTERNAL conmus'rxon ENGINE 3 Sheets-Sheet 2 Filed June 25. 1928 March 22, 1932. J. c. PETERSON I IN TERNAL COMBUSTION ENGINE Filed June 25, .1928 s Sheets-Sheet 5 Fig.6

shall be practically Patented Mar. 22, 1952 UNITED STATES PATENT OFFICE JULIUS O. PETERSON, OF CHICAGO, ILLINOIS INTERNAL COMBUSTION: ENGINE Application .aa June as,

My invention relates to internal combustion engines of the four stroke cycle type and the first, to provide means for practically complete expulsion of the products of combustion from the cylinder on the exhaust stroke and, second, to provide means for drawing into the cylinder, on the intake stroke, a charge of combustible mixture whose volume equal to the full volume of the cylinder.

urther objects of my invention are to accomplish the foregoing objects in such a way that the usual construction of the en ine' will require very little modification, an no difiiculties of manufacture shall be encountered, and that a minimum of-power shall be absorbed.

been connected to the Generally speaking, the ultimate-object of my invention is to increase the efliciency of the engine, which is to say, to get more power from an engine having cylinders of given di mensions and to decrease consumption per horsepower-hour.

Heretofore in internal combustion engines of the four stroke cycle type, the piston has crankshaft by a connecting rod in such a way that the distance from the head of the piston to the center of the upper connecting rod hearing has been constant.

In my'invention the piston comprises two 4 main parts which are so connected as to pertive motion of the two mit of :1 limited "relative motion between them in the direction of the longitudinalaxis of theicylinder. One of: these arts includes the head of the piston, and the other part includes the piston pin bearings, so that the piston to the center of the upper connecting rod hearing is variable within the limits of the relaparts of the iston.- As a consequence the path travelled y the piston head may be longer than the pathtraivelled by the upper end of the connecting ro I In anengine not equipped with my invention the piston head does not enter the compression chamber, and thefproducts of combustion remaining therein, at the endmf. the

principal objects of my invention are:

the amount of fuel ma. semi 110. 288,150.

exhaust stroke, are ordinarily termed the re sidual burned gas. The amount of residual burned gas varies with the compression ratio, the. latter term being applied to the ratio of the volume of the entire cylinder "to the volume of the compression chamber.

In automobile engines now being inanufactured in this country, the compression ratio varies from four to one to six to' one, with the trend toward the higher ratio, since experience shows that big er compression gives higher efiiciency. As experience shows that a compression ratio of six toone is practicable, I will assume that ratio for the purpose of illustrating the approximate increase 35 in power that results from the use of my invention. The residual burned gas will then amount to one-sixth of the total volume of the cylinder, or nearly 17%. v

The ressure necessary .to'force the products of combustion out of the cylinder throughthe exhaust valve, varies from about, one pound per square inch at low-speeds up to several pounds per square inch at high speeds, with about three-pounds per square inch for an average. The amount of suction necessary to draw the fresh fuel mixture into the cylinder through the intake valve varies similarly from low to high speeds, with about three pounds per square inch for an average. Assuming atmospheric pressure as fifteen pounds per square inch, the pressure onthe exhaust stroke is then eighteen pounds per square inch, and on the intake ,stroketwelve pounds per square inch. According to the laws of expansion of gases, volume increasing for reduced pressure and decreasing for redueed temperature, the 33% decrease in pressure, modified by the decrease in temperature, will increase the volume of the residual burned gas from nearly 17% to about20% of the volume of the cylinder during the in- .take stroke. At the end of the intake stroke,

' volume of the cylinder during the intake stroke. At the end of the intake stroke, then,

the contents of the cylinder will be 2.4% residual burned gas and 97.6% fresh fuel mixture. That is, 17.6% of the volume of the cylinder that was occupied by residual burned gas is now occupied by fresh fuel mixture. 88% of the residualv burned gas has been expelled from the cylinder and 22% more fuel mixture has been drawn into The ratio of residual burned gas to fuel mixture has been reduced from one to four to one to forty.-

The residual burned gas cannot be burned agairr, and on the .intake stroke it is mixed with the fresh fuel mixture which is drawn into the cylinder. The presence of the residual burned gas in the mixture renders it less combustible and harder to ignite, and in order that ignition shall take place, more fuel must be present in the mixture than would have to be if the residual burned gas were absent from the mixture. Reducing the residual burned gas to one part in forty, through the use of my invention, makes it practicable to ignite and burn a very much leaner fuel mixture,

so that while, a greater volume of fuel mixture is drawn into the cylinder on each stroke, a smaller amount of fuel is contained therein. Y While the accompanying drawings show one form that my invention may take, they are in the main illustrative, for other forms,

coming within the scope of my invention, are

practical and I do not limit my invention to what is shown in the drawings.

Figure 1 is a vertical section throughthe engine, on a plane containing thelongitudinal axis of one of the cylinders and perpendicular to the axis of the crankshaft, the piston, connecting rod and spark plugs not being in section; Figure 2 is a vertical section through the center of the piston on a plane containing, the longitudinal axis of the piston in bearings; Figure 3 is a horizontal section of the piston on a plane 3 3 of Figure 2; Figure 4 is a vertical section through part of the engine on a plane containing the longitudinal axes; of the cylinders showing part of the cylinder head and the upper end of one of the cylinders, with two valves and the top of the piston not in section.

igure 5 is a side view of one end of the cylinder head, showing the niches in which spark plugs are positioned; Figure 6 is aside view of the openings sa Figure 7 is a bottom view of one end of the cylinder head showing the openings in the bottom of the head; Figure 8 1s a top view of one end of the cylinder head, partly insection, showing in the center ahorizontal section on the lane 8 the right a horizontal section on a plane 8 8' of Figure 1, the spark plugs being omitted.

the cylinder.

one end of the cylinder head showing of the exhaust and intake pas-- 8 of Figure 1, and at parts, the piston slide 2 which contains the piston pin bearings 3 and the bushings 4, and the piston sleeve 5 which is'itself composed of two parts, the piston sleeveproper and the retaining ring 6 attached to the sleeve by the male and female screw threads 7 This construction-0f the piston sleeve permits the piston slide to be inserted in the and there held securely. The piston sleeve 5 has the piston which are positioned the piston rings 9, and the skirt 10. The upper and lower portions of the piston sleeve are cylindrical and of a diameter to fit the bore of the cylinder 11 with proper clearance. down the weight of the piston sleeve the skirt 10 has a smaller outer diameter than the upper and lower port-ions of the sleeve. The piston sleeve has a cylindrical inner surface of such fit with the cylindrical outer surface of the piston slide 2. In assembling the piston, the upper endof the connecting rod 12 is passed throu h the retaining ring 6 and the piston sliders then connected to the connecting rod with a piston pin (not shown) in the same manner that ordinary pistons are connected.

Piston sleeve 5 is then slipped over piston slide 2 and retaining ring-6 screwed into position, completing the assembly. The parts of the piston i their assembled relation are best shown in Figure 2.

This construction of the piston permits the piston sleeve and the piston slide to have a limited sliding motion relative to each other, in addition to the slidin motion of the piston in the cylinder. As w' l be shown later, the piston sleeve and the piston slide will cally have widely varying velocities, the velocity of the piston sleevebeing very high when the velocity of the piston slide is very low. In a high speed engine velocity may range as high as three to four thousand feet per minute. Consequently means is provided to prevent the shock which would occur when the arts reach their limits of relative motion. his means consists of two dashpots, one to absorb the energy of the parts for eachlimitof relative motion. In the retaining ring 6 is formed the annular groove 13, o substantially semieircular section at the bottom. The'outer wall of the groove is'formed by the inner surface of the piston sleeve, 6 forming the inner wall 15, which is slightly inclined so that the-top of the groove is wider than the bottom, which is just wide enou h to permit the ring 16, on ten slide 2, to enter. ..Oil is splashed on all the interior arts of, the" piston from the spray forme by the lubrication system of the engine, and

head 8, piston ring grooves n In order to keep" diameter'as to provide a sliding periodithe lip 14 of the retaining ring some of it collects in the iston sleeve the difference in the lower end 0 piscome together more 'oilis pushed along the inner surface of the piston sleeve into" the groove by the ring. As the two parts of the piston come together their energy is absorbed by the work done in the dashpot.

As the ring 16 enters groove 13 the oil. is forced out of the groove through the clean ances between the walls of the groove and the ring, and through the small holes 17, equally spaced around the bottom of groove 13, so that the parts come together gently without shock.

The surface of ring 16 is slightly flattened at the bottom, otherwise the ring fits the bottom of the groove 13 so as to give an adequate area of contact to support the pressure applied. When forces act that cause the parts of the piston to move in such a manner that ring 16 and groove 13 tend to separate, the cohesion of the ring and groove might hold them together were it not for the fact that the flattening of the bottom of the ring 16 and the holes 17 permit oil and air to enter the bottom of the groove and reduce the amount of the cohesion.

The annular groove 18 formed in the lower side of piston head 8, and the ring 19 on.

the upper end of piston slide 2, with the holes 20, equally spaced in the ring 19, are,

similarly formed to form the other dashpot, which operates in' a similar. manner. The clearances in the upper dashpot are somewhat smaller than those in the lower, and the holes 20 are a little smaller thanthe holes 17, as-the energy to be absorbed by the upper dashpot is somewhat greater than that to be absorbed by the lower, due to the force of gravity acting downward and accelerating the downward motion of the piston sleeve 5, while it retards its upward motion.

The amount of the relative motion between the piston slide and the piston sleeve is dependent on two factors, the compression ratio of the engineand the permissible maximumpossible movement, which will be explained later.

The cylinder block 21 has the cylinder 11 with the usual cylinder jacket 22, upper crank case 23 and bearings for the crankshaft 24 and crankshaft 25. The center of the crank pin 26 travels in the crankpin circle27. The oil pan 28 is shown in part. The cylinder 11 is of uniform bore throughout its lengthexcept for the conical surface 29 at the bottom,

to facilitate the insertion of the piston with 5 circular depression 34, which is of such depth the plane of the lower surface 31 of the cylinder head. This construction is best shown in Figure 4. This construction of the cylinder and cylinder head permits the piston head to approach the cylinder head with a minimum clearance, so that the volume occupied by the products of combustion at the end of the exhaust stroke, will be a minimum.

The circular depressions in which the valve I seats are positioned are of sufficient diameter so as not to interfere with the passage of the gases, and so as to permit the use of valves the sum of whose maximum diameters is only slightly less than the diameter of the cylinder.

Threaded holes 40 are positioned in the bottom of the niches 41 formed in one side of the cylinder head, to receive spark plugs 42. Similar threaded holes 43 are positioned in the bottom of the wells 44, formed in the top of the cylinder head, to receive spark plugs 45. This construction permits of the use of either one or two spark plugs for each cylinder. As experience shows that greater power for the same amount of fuel is obtained when two spark plugs for each cylinder are used, I have made provision for them in the novel manner, described. The bottom of the spark plugs is substantially flush with the lower surface of the cylinder head, so

inder head through passages 51, and from the cylinder head to the water manifold (not shown) through passage 52. 53 is a bolt hole for a bolt to hold the water manifold in position. 54 are bolt holes for bolts to hold the supports 55 for the rocker arm shaft 56 in position, and 57 are bolt holes for bolts to hold the cylinder head in position on the cylinder block. The valve guides-58 are positioned in the holes 59, and the valve springs 60 are received in the depressions 61.

As will be seen from the drawings, adequate space for the cooling water has been left in the cylinder head, and the gas passages and valve seats are adequately surrounded by water. As the cylinder head is symmetrical the complete head when the axis of the top of the crank pin circle.

with respect center and perpendicular, to its longer axis, for a four cylinder engine I simply the addition of an end on the right for the fourth cylinder, symmetrical with the end shownon the left for the first cylinder. For a six cylinder engine a right portion symmetrical to the left portion shown would be required, and for an eight cylinder engine, the same as for a six, with an additional ortion in the center similar' to that shown or two interior cylinders. As any suitable valve gear, ignition System, lubrication system, and so on may be used in the engine, the presence of such parts is as sumed.

, In such a system as that described, where a cylinder contains a piston comprising two parts capable of limited relative sliding motion cran k pin of a revolving crankshaft, the motion of the piston slide, being connected to the upper end of the connecting rod, is in a straight line, with a velocity varying from zero at the moments when the crank pin is at the top and bottom of the crank pin circle, to a maximum slightl in excess of the linear speed of the crank pm at the two moments connecting rod is tangent to the crank pin circle. For a connecting rod whose length is twice the diameter of the crank pin circle, approximately seventy-six degrees from the For longer connecting rods the an le will be greater.

For. convenience% will divide each stroke of the piston slide into two 'parts, calling the part during which the crank pin travels bewould require tween the bottom of the crank pin circle and a pointof tangency of the axis of the connecting rod, the lower part; and the remaining part, during which the crank pin travels between a point of tangency and the top of the crankiipin circle, the upper part. In designating the relative positions of the piston slide and iston sleeve with reference to each other, I w ll call the position when the piston head is nearest the piston pin, with theupper dashpot closed, the lower position of the piston sleeve; and the position when the piston head is farthest from the piston pin, and the lower dashpot closed, the upper position of the piston sleeve. y

During the lower part of an upward stroke and the upper part of a downward stroke, then, the piston slide and the piston sleeve are accelerated together, and at the end of that part of the stroke, both parts ofithe piston;have attained the same maximum veloc necting rod, but the piston sleeve, being capau ble of motion relative to the piston slide, has

to a vertical plane through its connected by a connecting rod to the these two points are each to pull it down.

and thelower part of a downward the piston slide is retarded by the cona motion which will be considered separately for each stroke of the cycle.

At the start of the exhaust stroke the piston sleeve is assumedto be in its lower position, then.,- At the end of the *lower part of the stroke the piston sleeve has attained its maximum velocity and has stored in it energy roportional to its weight and to the square energy being expended in overcomi ngtheseresistances.

If the speed of the engine is very low, the energy of the piston sleeve will not hesufiicient to overcome entirely the resistances and permit the sleeveto get up to its upper position at the end of the exhaust stroke, but as the speed of the engine increases, the energy of the piston sleeve increases much faster and soon is sufiicient not only to overcome the resistances and cause the sleeve to rise to its upperposit'ion at the end ofthe stroke, but

to require that the lower dashpot absorb the excess energy and bring the piston sleeve to rest. WVith the piston sleeve in its upper osition at the end of the stroke, the piston ead is as close to the cylinder head as the necessities of good mechanical clearance permit, and practically all the products of combustion are forced out of the cylinder, reducing the volume of residual burned gas to a minimum.

At the start of the intake stroke, then, the piston sleeve is in its upper position. The piston slide pulls it down until its maximum velocit is attained at the end of the upper part 6 the stroke. in the case of the exhaust stroke, it has acquired energy and this energy is used in the lower part 0 the stroke in overcoming the resistance of friction and the difference in pressure between the air in the crankcase and the fuel mixture entering through the intake valve. Gravity acts to accelerate the motion of the piston sleeve instead of to retard'it. The piston sleeve moves to'its lower position at the end of the stroke, the. energy still remaininglbeing absorbed by the upper dashpot and the sleeve being brought to rest. Substantially ,the entire volume of the cylinder is thus filled with fresh fuel mixture. A

If the speed of the engine is too slow to cause the piston sleeve to move entirely up to 5 its upper position on the exhaust stroke, it is evident that all the products of combustion will not be forced out of the cylinder, and that at the start'of the intake stroke the piston sleeve will descend due to gravity until the piston slide catches up to it and begins The upper dashpot, in such a case has far more than sufiicient capacity to prevent any shock fto the ton-when they come toget er. The piston sleeve will descend nearlyto its lower posiarts of the pis iao tion, however, but the upper dashpot may not be entirely closed.

' At the start of the compression stroke, then, the piston sleeve is in its lower position. As on the exhaust stroke, it attains its maximum velocity at the end of the lower part of the stroke, and acquires energy. But whereas on the exhaust stroke the pressure of the burned gas varies from almost nothing up to a few pounds per square inch, on the compression stroke, withboth valves closed, the pressure of the compressed fuel mixture is much higher- In an engine having a compression ratio of six to one, at average speed, the pressure at the beginning of the upper part of the stroke is from twenty to twenty-five pounds per s uare inch, and at the end of the stroke is rom one hundred to one hundred and twenty-five pounds per square inch. With a lower compression ratio the pressures will be somewhat less, and with the throttle nearly closed the pressures will be much less. But with a nearly closed throttle the speed of the en 'ne .will ordinarily be low. Consequently t .e energy of the. iston sleeve will not be sufficient to entire y overcome this pressure and the piston sleeve will remain in its lower position, leaving, at the end of the stroke, the required space for the compression chamber.

At the start of the power stroke, then, the piston sleeve. is in its lower position. The pressure of the gas keeps it there throughout the entire stroke, and at the end of the stroke it is in the position assumed for it at the start of the exhaust stroke, and the cycle is completed.-

It will be seen that on the compression and power strokes the piston sleeve remains in its lower position, there being no relative mo-' tion of the piston sleeve and the piston slide.

The action of the piston on these strokes is the same as that of an ordinary piston.

There is an exception to theabove statement. In the case when the throttle is closed,

or nearly closed, while the engine is running 1 at high speed, there willbe but little fuel mix ture in the cylinder on the compression stroke and the energy in the piston sleeve Wlll be sufiicient .tocompress the fuel mixture into a volume less than that of the normal compression cha'mber, the piston sleeve leaving Its lower position but notrising as high as its upper position. The upper dashpot is opened. As the amountof fuel mixture was small, the force of the explosionon the power stroke will not be great and by the time that the piston sleeve startsto descend the iston slide will also have started'downwar As the two parts .of the piston come .together they willhe travelling in the same direction and the upper dashpot' will be required to absorb sufficient energy to prevent. any shock. The dashpot must have suflicient capacity to do this. I p

The distance that the piston sleeve can travel during the upper part of the exhaust stroke cannot safely exceed a certain definite limit. The sleeve must be brought to rest before the piston s'lide starts downward on the following intake stroke and sufficient time must be allowed for this to take place.

A simple calculation shows that while the to bring the piston sleeve to rest, the maxi mum distance the sleeve should move maybe put at .25 of the diameter of the crank pin circle, which is the length of the compresslon chamber for a compression ratio of five to one. Thus for compression ratios of five to one or greater, the piston sleeve may have sufficient motion relative to the piston slide for the practically complete expulsion of the products of combustion. For compression ratios less than fi-ve to one, while the amount of the products of combustionexpelled will be less, it will still be suflicient to greatlyimprove engine performance.

The relative motion of the piston parts is further limited by the fact that the piston head must not strike the cylinder head. In an engine having a compression ratio of six to ene, the length of the compression chamher, in an engine such as I have described, would be .2 of the diameter of the crank pin circle. Allowing .02 of the diameter for mechanical clearance, the relative motion of the piston parts would be .18 of the diameter, which is only about three-fourths of the permissible maximum and should give excellent results over a wide range of engine speed.

I claim I 1. A piston for, an internal combustion engine comprising in combination a piston sleeve, a piston slide mounted within the sleeve for limited free movement relative thereto, and means for cushioning the piston slide and sleeve against shock upon reaching the limiting ranges of relative movement.

2. A piston for an internal combusition engine comprising in combination a piston sleeve, a piston slide mounted within the III III

limited relative movement of the slide and sleeve including a dash-pot arrangement.

4. A piston for an internal combustion engine comprising in combination a piston sleeve, a piston slide mounted within the sleeve for limited movement relative thereto, and a retaining cap fitted-to the base of'the piston sleeve and having an upwardly extending annular lip cooperatin with the base of the piston slide to form a ash-pot.

5. A piston for an internal combustion engine comprising in combination a piston sleeve, a piston slide mounted within the sleeve for limited movement relative thereto, a retaining cap fitted to the base of the piston sleeve and having an upwardly extending annular lip cooperating with the base of the piston slide to form a dash-pot, and a second dash-pot comprising an annular groove in the top of the piston sleeve cooperating with the top of the piston slide.

6. A piston for an internal combustion engine comprising in combination a piston sleeve, a piston slide mounted within the sleeve for limited movement relative thereto, a retaining cap fitted to the base of the pis ton sleeve and having an upwardly extending annular lip cooperating with the base of the piston slide to form a dash pot, and a second dash pot comprising an annular groove in crating with the top of the piston slide, said dash pots being provided with relief vents.

7. An internal combustion engine comprising a cylinder, a piston within the cylinder, a cylinder head for closing said cylinder, valves within the cylinder head located above the cylinder and arranged so that their heads lie in a plane with the base of the cylinder head, when the valves are in a substantially closed position, said piston comprising a piston sleeve having a slide mounted therein for limited free movement relative thereto and being adapted to travel the full length of the cylinder for completely scavenging the cylinder of residual burnt gases.

8. In an internal combustion engine comprising in combination a cylinder, a piston within the cylinder, said piston comprising components freely movable for a limited distance relative to each other to vary the effective length of the piston stroke, a cylinder head closing the top of the cylinder, intake and exhaust passages within the cylinder head, and valves for controlling the opening and closing of said passages, theheads of said valves being arranged within the cylinder head so as tolie in the plane of the lower face of the cylinder head when the valves are in a closed position. v

9. A piston for an internal combustion engine comprising in combination a piston sleeve, a piston slide mounted within the sleeve for limited movement relative thereto, means for cushioning the said limited rel-.

the top of the piston sleeve coopative movement of the slide and sleeve, said means comprising an annular groove'cooperating with the base of the piston slide.

10. A piston for an internal combustion engine comprising in combination a piston and means for cushioning the said limited relative movement of the piston sleeve and slide including annular grooves adjacent the top and bottom of the piston sleeve and cooperating with the top and bottom respectively of the piston slide for forming dash pots.

12. An internal combustion engine comprising in combination a cylinder, a piston within said cylinder, a cylinder head for clos ing the top of said cylinder, said piston comprising a piston sleeve having a piston slide mounted therein for limited free movement relative thereto, and means for causing said sleeve to travel a maximum distance during the exhaust and intake strokes, and a somewhat smaller distance during the compression and power strokes.

13. An internal combustion engine comprising in combination a cylinder, a piston within said cylinder, a cylinder head for closing the top of said cylinder, said piston comprising a'piston sleeve having a piston slide mounted therein for limited free movement relative thereto, a dash pot for cushioning the limited relative movement of the piston sleeve and slide, and means for causing. said sleeve to travel a maximum distance during the exhaust and intake strokes, and a somewhat smaller distance during the compression and power strokes.

14. An internal combustion engine comprising in combination a cylinder, a cylinder head for closing the top of said cylinder, a piston within the cylinder, said piston comprising components freely movable for a limited distance relative to each other to vary the effective length of the piston stroke and limited at each end of their relative movement by a dash pot, valves for controlling the gaseous content of the cylinder, and ignition means for producing'an explosion within the cylinder, said piston having a maximumtravel under certain conditions to a point adjacent the lower face of the piston head, said valves and ignition means being 'so positioned with respect to the cylinder as to permit a substantially complete expulsion of the gaseous content of the cylinder when the piston travels its maximum distance.

15. An internal combustion engine comprising in combination a cylinder, a cylinder lead, a piston within the cylinder, a crank shaft, a connecting rod connecting the piston to the crank shaft, said piston comprising outer and inner members freely movable for a limited distance relative to each other to vary the length of the piston stroke during different conditions of engine operation,

and a dash pot for cushioning the limited movement of the outer and inner piston members.

16. A piston for-an internal combustion engine comprising in combination an outer cylindrical member closed at one end by a head, an inn'er cylindrical member slidably mounted within the outer member for limited movement relative thereto, means provided on said inner member for connection with a connecting rod, a'retaining cap fitted to the base of the outer member and having an inwardly and upwardly extending annula'r lip forming an interior groove at the base of said outer member, an annular groove formed in the lower face of the outer cylinder member, beads provided on the upper and lower edges of the inner cylinder for c0- operating with the annular grooves at the top and bottom of the outercylinder member for forming dash pots to cushion the "relative movement of the two members.

JULIUS C, PETERSON. 

